O2 sensors...to replace one, or to replace all?

[RangerPilot]

In light of one of my O2 sensors crapping out last night, a couple of friends and I were having a discussion about them.

Friend A suggested I just pick up a new O2 sensor and replace the dead one (bank 2, sensor 1).

Friend B suggested that I replace all of them in a group and that replacing one alone could possibly cause more problems than solutions.


Before I state what group I agree with, I'd like to get some thoughts from you guys. What's your method, and why?

 

[5.0]

How many is there?

I would replace the sensors before the cats and not worry about the ones after the cats.

 

[73F100Shortbed]

You should be fine with replacing just the bad one. I haven't seen a car have more problems from replacing just the bad one. It is a good suggestion to replace both before the converter though.

 

[Trucker_Eric]

only replace one. they dont go out often, and they are a pain in the ***, any way you look at it. you also need the special socket for them if you want to do it the easy way, or you can do it the hard way with an open end wrench

 

[73F100Shortbed]

The special socket is always a good way to go, but you can cut the wires off of the old sensor and used the closed end. To install the new sensor use the open end and anti-sieze. 7/8" wrench.

 

[CowboyBilly9Mile]

Given that the Ford dealer parts department here tells me that these are consider to be life of vehicle parts, I'd only replace the one that has proven itself to be bad.